Simulation of a data center cooling system in an emergency situation

The paper deals with keeping server rooms at reasonable air temperature in the case of an electrical power failure in a data center and with building performance simulations used to support emergency power planning. An existing data center was analyzed in detail with respect to the possibilities of emergency cooling. Based on the assumption that the thermal capacity of already chilled water can be used to prolong functionality of the cooling system when the roof chillers are out of operation, a backup power supply was designed for Computer Room Air-Conditioning and even for the cooling liquid circuit pumps (i.e. not for the roof chillers). Special models representing the data center indoor environment and cooling system, including a detailed model of the Computer Room Air Conditioning (CRAC) units, were developed in order to estimate the time period during which the internal air temperatures in the server room will not exceed the limit. The numerical model of the server room and the cooling system was built in the TRNSYS software and calibrated by measured data acquired from a real power outage situation. The results and conclusions obtained from the performed analyses and simulations helped to improve the emergency power plan of the data center. The study also forms the basis for the development of an emergency decision algorithm that will included in the novel supervisory control platform: GENi

Experimental and numerical study of local mean age of air

This paper presents the results from the experimental and numerical study of a room with mixing ventilation, focused on the local mean age of air (LMA). The measurements were performed using the tracer gas concentration decay method. The numerical predictions were obtained from the computational fluid dynamics (CFD) module of the latest version of the ESP-r software

Simulation to support passive and low energy cooling system design in the Czech Republic

This paper deals with the passive and low energy cooling technologies in the Czech Republic. The role of computer simulation in low energy building design and optimization is discussed. The work includes buildings and systems analysis as well as climate analysis in order to estimate the potential of passive and low energy cooling technologies. The former is based on case studies, which include both building simulation and monitoring

Analytical approach to transient heat conduction in cooling load calculations

The paper briefly reviews four existing analytical methods for the solution of the Fourier’s equation in cooling load calculations. The performance of nine different procedures (the four methods and their modifications) is presented on an example of heat transmission through a heavy wall under realistic external conditions. For the current case it was proved that the admittance method gives results similar to those obtained by the periodic response factors (PRF) approach, which is normally considered to be more advanced. Possible errors were found in the previously published coefficients for one of the PRF modifications

Computer simulation and measurements of a building with top-cooling

This paper deals with the use of computer simulations both for design support of a new building including its heating, ventilation and air-conditioning (HVAC) systems and for optimization of the HVAC control strategy during operation of the completed building. In the early design phases for a new commercial building in Prague computer simulations were carried out in view of possible effects of night cooling ventilation. Predictions of the indoor environment and energy consumption for various options regarding cooling capacity and different outdoor ventilation rates supported the HVAC system design which included daytime top-cooling and night ventilation with outdoor air combined with accumulation of cold in building constructions. After completion of the building, occupants' complaints and a set of measurements indicated some problems with the HVAC, which were subsequently solved. Long-term monitoring and further computer simulations were performed in order to optimize the control strategy of the top-cooling system

Design and commissioning of the low-energy office building in Prague

This paper deals with the use of computer simulations both for design support of a new building including its heating, ventilation and airconditioning (HVAC) systems and for optimization of the HVAC control strategy during operation of the completed building. In the early design phases for a new commercial building in Prague computer simulations were carried out in view of possible effects of night cooling ventilation. Predictions of the indoor environment and energy consumption for various options regarding cooling capacity and different outdoor ventilation rates supported the HVAC system design which included daytime top cooling and night ventilation with outdoor air combined with accumulation of cold in building constructions. After completion of the building, occupants' complaints and a set of measurements indicated some problems with the HVAC, which were subsequently solved. Long-term monitoring and further computer simulations were performed in order to optimize the control strategy of the top cooling system